I recently found two, currently free, markdown editor apps, TAIO and OneMarkdown, for iOS that each use iCloud to store files. It’s just a matter of setting up a folder in iCloud as a vault for Obsidian to access these files in Obsidian. I am still assessing which is better for my uses. Right now, that is just to have a mobile markdown editor on which to enter text for later use in Obsidian. Both seem to do that admirably.
OneMarkdown was written as a light editor by the developers of MWeb. It allows a split markdown and preview screen like Obsidian. There is also a MacOS version of OneMarkdown. There are notes from the developer stating that OneMarkdown will be included in MWeb at some point, but I don’t know exactly what they mean for the long-term viability of the app.
TAIO will edit files but will also record snippets, which might be useful to some. It also allows one to use Clipboard in iOS as markdown.
I am just starting to explore these. If others are interested in experimenting, we might start a new topic exploring either or both of these and follow and, perhaps, influence their development long-term.